Alloy-steel building material



Patented Sept. 10, 1929.

UNITED STATES PATENT OFFICE.

WALTER HfiLSBRUCH, OF DORTMUND, GERMANY, ASSIGNOB TO THE FIRM VEREIN- IGTE STAHLWERKI; A. G. DUSSELDORF.

ALLOY-STEEL BUILDING MATERIAL.

1T0 Drawing. Application filed May13, 1927, Serial No. 191,275, and in Germany May 22, 1926.

Of recent times for metal constructional work (bridges and similar structures) a steel of especially great toughness and duo tility has been proposed, which is endowed with these properties by an increased addition of silicon, in a quantity of from 0.5 to 1.5%. Now by virtue of long and exhaustive experiments it has been found that this steel has a very great drawback hampering its general use; it is subject to a far greater degree than pure carbon steel to corrosion attack by the atmosphere, and water which contains salts and acids, in particular sea water and the like. In this way a large part of its otherwise good properties is counterbalanced to a considerable extent, and its desirable introduction to practical use is greatly hampered, the consequence of which is that'the known silicon steel has under certain circumstances to be set aside for the construction for example of iron bridges in the neighborhood of seas or chemical factories,

of ships, iron pillars in damp ground and the like. Also in plants exposed solely to normal rust attack, the strong corrosive phenomena may lead to very prejudicial results;

This inconvenient property is all the more surprising because silicon is a prominent deoxidizing medium and, furthermore, iron highly alloyed with silicon is even rendered especially capable of resisting the action of acids. I

Now according to the invention it becomes possible in a surprisingly simple man: ner to open up for the silicon steel those fields hitherto closed to it, provided a small addition of copper be incorporated with it, whereby, as numerous experiments have demonstrated, its power of resisting corrosion is increased to a remarkable degree. This fact owing to the abnormal corrosion of this known silicon steel had not previously been foreseen at all, and also in View of analogous deductions not to be assumed with certalnty.

The effective addition of copper lies within the limits of 0.1 to 0.5%.

What I claim and desire to secure by Letters Patent of the United States is:

1:"A steel for building material having corrosion resisting properties which, with otherwise normal composition, consists of WALTER HULSBRUCH. 

